Metabolic changes in the subtropical frog Boana pulchella during experimental cooling and recovery conditions.

Frogs have developed biochemical and physiological adaptations to occupy diverse ecological niches on Earth successfully. Survival in frozen states is a fascinating strategy made possible by evolving adaptations to produce cryoprotectant solutes. The hylid frog Boana pulchella thrives in South American regions with cold climates, remaining active while enduring sporadic subzero temperatures during winter. The species' metabolic changes during subzero exposure remain unclear. Therefore, we exposed B. pulchella to cooling and recovery, assessing plasma and tissue metabolite changes. Cooling significantly reduced urea concentrations in plasma (P = 0.033), muscle (P = 0.001), heart (P = 0.009), and brain (P = 0.041) compared to acclimation. Liver glucose oxidation and glycogen synthesis were lower in cooling and recovery than in acclimation (P < 0.0001 and P = 0.0117, respectively). Muscle glycogen synthesis was lower in recovery than acclimation (P = 0.0249). These results demonstrate B. pulchella's physiological strategies during subzero exposure, likely reflecting species-specific evolutionary adaptations for brief subzero exposures that enable winter survival in its natural habitat. [Display omitted] • Boana pulchella, a South American frog, did not freeze when exposed at −2.5 °C for 24 h. • Between acclimation, cooling, and recovery exposure, B. pulchella showed changes in tissue metabolites. • During cooling exposure, B. pulchella had lower urea concentrations in tissues and plasma. • During cooling and recovery showed lower glucose oxidation and glycogen synthesis from glucose in the liver. • Metabolic adjustments could provide a strategy to survive in a seasonal habitat with brief negative temperature periods. [ABSTRACT FROM AUTHOR]